Surgical planning for orthognathic surgery traditionally combines various diagnostic methods to create a surgical plan and/or to construct a surgical splint that can transfer the surgical plan to the patient in the operating room. According to more recent methods, a 3-D computed tomography (CT) model of the patient's skull including the patient's mandible, maxilla, and dentition is obtained using a CT scanner. While the CT scanner provides a good representation of the patient's bone structure, it is not capable at times of accurately representing the patient's dentition (i.e. teeth). For example, the dentition represented in the CT model may be obscured or otherwise include “artifacts” due to orthodontic metal brackets, dental fillings, or prosthesis on or near the patient's dentition.
To create a 3-D computer model having a good representation of both the patient's bone structure and the patient's dentition, a dental computer model of the patient's dentition is typically obtained by scanning a negative of an impression (i.e. a plaster cast) of the patient's dentition with a laser scanner or a CT scanner. Because a plaster cast of the dentition, and not the dentition themselves is scanned, the virtual dental model is not obscured or otherwise “scattered” due to the metal brackets, fillings, or prosthesis. The virtual dental model is then combined with the CT model of the patient's skull to thereby form a composite computer model that has virtual dentition void of any artifacts. The composite computer model is used to create the surgical plan and/or surgical splint.
To align the dental computer model with the dentition of the CT model, metal fiduciary markers are currently used during both the CT scan of the patient's skull and the scan of the plaster cast. The fiduciary markers of the dental computer model are then aligned with the fiduciary markers of the CT model to form the composite computer model. While the current method is capable of forming a composite computer model that is used to create an orthognathic surgical plan and/or surgical splint, the method is time consuming. Moreover, there remains a desire for more accurate surgical plans and/or surgical splints than those currently provided.